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Dilated cardiomyopathy (DCM) is a myocardial disorder characterized by ventricular dilation (LV or biventricular) and systolic dysfunction, with a broad etiological spectrum, comprising numerous genetic and non-genetic causes. Cardiac magnetic resonance (CMR) has become an important tool in guiding the etiological diagnosis in DCM. We present the case of a 37-years old man admitted to our department in order to investigate the diagnosis of DCM using CMR. Cine imaging showed mild left ventricular (LV) dilatation and moderate systolic (LV ejection fraction = 42%) dysfunction, but also apical hypertrabeculation meeting the criteria for non-compaction and late gadolinium enhancement (LGE) images revealed mid-wall fibrosis in the basal and midventricular segments of the inferior interventricular septum (IVS) – typical of non-ischemic DCM. Complete family history revealed the diagnosis of DCM in the mother of the patient and in the maternal grandfather, who had died at 87. After genetic testing of the index patient showed a pathogenic mutation in the TTN (titin) gene (c.79273A>T), cascade genetic testing followed, for his mother, sister, uncle and two cousins who all came back positive for the same mutation. CMR examination of the mother done 6 years prior demonstrated severe LV dilatation and systolic dysfunction (LV ejection fraction = 23%), LV non-compaction and mid-wall IVS fibrosis. CMR examination was performed for the other members of the family and discovered pathological findings in the uncle (normal LV volume and function, but focal mid-wall fibrosis in the inferior IVS) and the male cousin (LV non- compaction), while the female cousin had a normal exam. Using CMR and genetic testing, this case report proves the phenotypic heterogenicity of a completely penetrant titin mutation in the same family. Moreover, CMR is shown to be essential in DCM evaluation, having the ability to guide etiologic diagnosis and to detect alterations such as fibrosis and non-compaction in the absence of LV dilation or dysfunction.

PRKAG2 syndrome (PS) is a rare, early-onset autosomal dominant phenocopy of sarcomeric hypertrophic cardiomyopathy (HCM), that mainly presents with ventricular pre-excitation, cardiac hypertrophy and progressive conduction system degeneration. Its natural course, treatment and prognosis are significantly different from sarcomeric HCM. The clinical phenotypes of PRKAG2 syndrome often overlap with HCM due to sarcomere protein mutations, causing this condition to be frequently misdiagnosed. The syndrome is caused by mutations in the gene encoding for the γ2 regulatory subunit (PRKAG2) of 5′ Adenosine Monophosphate-Activated Protein Kinase (AMPK), an enzyme that modulates glucose uptake and glycolysis. PRKAG2 mutations (OMIM#602743) are responsible for structural changes of AMPK, leading to an impaired myocyte glucidic uptake, and finally causing storage cardiomyopathy. We describe the clinical and investigative findings in a family with several affected members (NM_016203.4:c.905G>A or p.(Arg302Gln), heterozygous), highlighting the various phenotypes even in the same family, and the utility of genetic testing in diagnosing PS. The particularity of this family case is represented by the fact that the index patient was diagnosed at age 16 with cardiac hypertrophy and ventricular pre-excitation while his mother, by age 42, only had Wolff–Parkinson–White syndrome, without left ventricle hypertrophy. Both the grandmother and the great-grandmother underwent pacemaker implantation at a young age because of conduction abnormalities. Making the distinction between PS and sarcomeric HCM is actionable, given the early-onset of the disease, the numerous life-threatening consequences and the high rate of conduction disorders. In patients who exhibit cardiac hypertrophy coexisting with ventricular pre-excitation, genetic screening for PRKAG2 mutations should be considered.